The present invention relates to explosive warheads of the rod-fragment type and, more particularly, to means for controlling the motion of the rods during their outward flight.
Several factors strongly influence the effectiveness or, in other words, the `kill` capacity of fragmentation warheads such as are used, for example, against target aircrafts in surface-to-air missile systems. One such system employs a so-called 360.degree. planar focused-fragment warhead which, when detonated, explosively drives high velocity fragments in all directions. The lethality of such warheads has been improved by focusing techniques and also by maximizing the striking energy-density.
It also has been recognized that, although such warheads are reasonably effective when the hit is in particular locations such as the location of the compressors or turbines of the aircraft, their lethality is not as effective when the hit occurs only in the structural portions. This relative ineffectiveness obviously is a matter of some concern and various efforts to improve this aspect of performance have been made. One such effort, for example, has been the use of long rod-type fragments rather than the more commonly used wires or other smaller fragments. In this regard, it has been recognized that a hit by a relative long fragment is capable of producing more disabling structural damage than normally would be caused by the smaller fragments. Such a rod arrangement is disclosed in U.S. Pat. No. 3,228,336 "Rod Warhead" issued Jan. 11, 1966 to Marvin L. Kempton. As there disclosed, the fragments of the warhead are provided by a plurality of rods connected or hinged together at their end portions in such a manner that the detonation of the explosive charge expands the rods at high velocity into a substantially continuous loop or ring for projection toward the target. Thus, the target or aircraft is struck by a substantially continuous string of elongate fragments capable of producing lethal structural damage. Although this `loop`-type of rod arrangement is excellent against some targets, it is not adapted for use against the very high speed targets which presently are of primary concern.
The use of elongate, discrete as opposed to continuous rods has been considered and their advantages, of course, appreciated. However, experimentation has shown that the pattern of these rod-type fragments on the target has been of such a discontinuous nature as to result in a high likelihood of missing various structural members. For one reason, the use of the longer rods obviously limits or reduces the number of fragments in the warhead and, of equal significance, the outward flight of such rod-type fragments is of such an uncontrolled nature that the fragments strike the target and produce somewhat of a `cannonball effect` resulting again in reduced warhead lethality due to the likelihood of missing the significant structural members. Another factor which limits their effectiveness is produced by what is known as a tendency for a polar drift, or, in other words, a tendency for the pattern to spread in an axial direction rather than be driven radially into the target.